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New research published in the Journal of Sleep Research suggests that maladaptive personality traits are linked to poor sleep health. The findings indicate that individuals who exhibit higher levels of negative emotions, social detachment, or disinhibition tend to report lower sleep quality and efficiency. While genetic factors explain a portion of this relationship, the study suggests that environmental influences and potential causal processes also play a significant role.
Sleep is essential for maintaining physical and mental well-being. Past scientific inquiries have established clear connections between insufficient sleep and various health issues, including cardiovascular disease, anxiety, and depression. To improve sleep outcomes, scientists attempt to identify the psychological factors that influence how well people rest.
Many previous studies have focused on the relationship between standard personality traits, such as those in the “Big Five” model, and sleep patterns. However, less attention has been paid to how maladaptive or problematic personality traits relate to sleep.
“The motivation was twofold. First, sleep is very important to health and daily functioning, and we want to further explore the predictors of everyday sleep,” said study author Ziyu Ren, a PhD candidate in the Department of Psychology at the University of Minnesota, Twin Cities.
“Second, as maladaptive personality traits are becoming more widely used in the DSM-5 Alternative Model for Personality Disorders, the continuum framework of personality has received more attention. However, most current work on personality and sleep links has focused on adaptive personality traits. We want to extend this literature by looking at the maladaptive end of the continuum and testing how it relates to sleep outcomes.”
The Alternative Model of Personality Disorders from the DSM-5 focuses on specific domains of personality that can impair functioning. These domains include Negative Affectivity, Detachment, Disinhibition, and Psychoticism. Understanding the connection between these difficult traits and sleep could help clinicians develop better interventions. For instance, if specific personality traits directly contribute to sleep disturbance, treating the personality issue might alleviate the sleep problem.
To investigate these relationships, the team analyzed data from two large, longitudinal twin cohorts. The sample included participants from the Colorado Twin Registry and the Minnesota Twin Family Study. The final analysis included 2,802 individuals. This group comprised 980 complete twin pairs, consisting of 641 monozygotic (identical) pairs and 339 dizygotic (fraternal) same-sex pairs. The average age of the participants was approximately 35 years old. The majority of the sample was female and white.
Participants completed assessments remotely between 2018 and 2021. To measure sleep habits, the researchers used the Pittsburgh Sleep Quality Inventory. This widely used tool assesses several aspects of sleep. It measures sleep duration, which is the total hours slept. It calculates sleep efficiency, which is the percentage of time spent in bed actually sleeping. It also produces a score for overall subjective sleep quality.
For personality assessment, the participants completed an abbreviated version of the Personality Inventory for DSM-5. This measure evaluates four specific maladaptive domains. Negative Affectivity involves the frequent experience of negative emotions like anxiety and anger. Detachment refers to a tendency to avoid social and emotional experiences. Disinhibition is characterized by impulsivity and a focus on immediate gratification. Psychoticism describes unusual beliefs and eccentric behaviors.
The researchers utilized a twin study design to analyze the data. This method allows scientists to estimate the relative contributions of genetics and the environment to observed traits. Identical twins share nearly all their genetic material, while fraternal twins share about half on average. By comparing the similarities between these two types of twin pairs, the researchers could determine how much of the correlation between personality and sleep is due to shared genes.
They also employed a co-twin control design. This analysis looks at differences within twin pairs to test for potential causal effects, controlling for shared genetic and environmental backgrounds.
The results showed that all four maladaptive personality domains were associated with poorer sleep. “One thing that stood out is that, compared to what meta-analyses report for normative personality traits and sleep, the maladaptive personality domains showed stronger correlations overall,” Ren told PsyPost. “This suggests maladaptive traits’ potential for understanding and predicting health related functioning.”
However, the strength of these associations varied depending on the specific aspect of sleep being measured. The associations were generally small when looking at sleep duration. This indicates that maladaptive traits are only weakly linked to the actual number of hours a person sleeps.
The associations were medium in strength for sleep efficiency. Individuals with higher levels of maladaptive traits tended to take longer to fall asleep or spent more time awake in bed.
The strongest associations appeared in relation to overall sleep quality. The data revealed large to very large correlations between maladaptive traits and poor sleep quality. This suggests that while these individuals might sleep for a similar amount of time as others, their subjective experience of that sleep is significantly worse.
Among the specific personality domains, Negative Affectivity and Detachment consistently showed the strongest links to sleep problems. Individuals who frequently experience negative emotions or who withdraw socially were the most likely to report poor sleep. The researchers also calculated a “p-factor,” which represents a general level of personality pathology. This general factor also showed a strong negative correlation with sleep quality.
“People who report higher levels of maladaptive personality domains, especially higher Negative Affectivity or more Detachment, also tend to report poorer sleep,” Ren said. “This shows up as slightly shorter sleep duration, taking longer to fall asleep, and noticeably worse overall sleep quality.”
The biometric analysis revealed that both sleep characteristics and maladaptive personality traits are moderately heritable. This means that genetics play a significant role in determining these traits. The study found that shared genetic factors accounted for a moderate to large portion of the relationship between personality and sleep. In other words, the same genetic variations that predispose someone to traits like Negative Affectivity also predispose them to sleep difficulties.
However, genetics did not explain the entire relationship. The co-twin control analysis provided additional nuance. When the researchers examined identical twins, they found that the twin with more severe maladaptive traits still tended to have worse sleep than their co-twin. Since identical twins share the same genetic code, this finding implies that the relationship is not solely due to genetic confounding.
This persistence of the association within identical twin pairs supports the possibility of a causal relationship. It suggests that having higher levels of maladaptive traits may directly lead to worse sleep. For example, a person with high Negative Affectivity might ruminate on worries before bed, making it difficult to fall asleep. Alternatively, it could mean that poor sleep exacerbates maladaptive personality traits. Sleep deprivation often increases irritability and emotional reactivity, which are hallmarks of these personality domains.
The study also highlighted the role of non-shared environmental factors. These are unique experiences that one twin has but the other does not. The analysis showed that these unique environmental influences also contribute to the link between personality and sleep. This was particularly true for sleep duration, where external constraints like work schedules or family obligations likely play a larger role than personality.
“Genetics can partially explain why these traits and sleep problems go together, but not fully,” Ren explained. “There are also environmental influences, and the pattern is consistent with potential causal processes. From a practical standpoint, for example, this suggests sleep difficulties may be one useful and modifiable target when someone is also experiencing high levels of chronic negative emotions or social withdrawal.”
There are some limitations to this study that should be considered. The researchers relied on self-reported measures for both sleep and personality. It is possible that individuals with high levels of negative emotion simply perceive their sleep as worse than it objectively is. This response bias could inflate the strength of the observed associations.
“A key caveat is about causality,” Ren noted. “In the paper, we note that the pattern of evidence is in line with causal interpretations, but that does not establish a causal relationship. Readers should treat the findings as supportive of possible causal links and shared mechanisms, not as proof that tendency in maladaptive domains cause poor sleep.”
“I would also encourage more replication in different samples. One key limitation of our study is that we included four of the five maladaptive domains, so future work should capture the full maladaptive trait framework. It would also be valuable to incorporate objective sleep measures, such as actigraphy, to strengthen and consolidate these findings.”
Longitudinal studies that follow people over time could help clarify the direction of the causal arrow, determining whether personality changes precede sleep problems or vice versa. Future research could also incorporate objective measures of sleep. Tools such as actigraphy watches can track sleep patterns through movement, providing data that is less subject to personal bias.
“My long-term goal is to understand the role of PID-5 maladaptive traits in organizational and work-related contexts,” Ren told PsyPost. “This study is one step showing that PID-5 traits can meaningfully predict a well-being outcome reflected in sleep. Next, I plan to examine PID-5 links with broader well- being and key workplace outcomes, and test when it adds value beyond normative personality traits.”
The study, “Sleep and Maladaptive Personality Traits: A Twin Study,” was authored by Ziyu Ren, Jarrod M. Ellingson, Christian Hopfer, Robert F. Krueger, Zlatan Krizan, Kristian E. Markon, Deniz S. Ones, Zoë Panchal, J. Megan Ross, Scott Vrieze, Stephanie M. Zellers, and Matt McGue.
